Soliton transmission technologies have become the most important field of research in optical communications. The aim of the present invention is to provide a soliton transmission method with enhanced data transfer rate especially for long range WDM based fiber-optic communications. This is done by introducing solitons which consist of multiple partially overlapping short pulses. Other aim is to provide data packets which are based on such pulse group solitons, and also introduce a new kind of packet switching system.